Lock and Key
by KayValo87
Summary: POST-SERIES While investigating the murder of a top ranking physicist, the team uncovers a secret that may cost a young boy his life.
1. Chapter 1

Alright, so I know I am only, almost, halfway done with my "ABC" story, but this one would just NOT leave me ALONE! (which I guess is good for you guys, since it gives you more to read.)

Anyway, as i said in the summarry, this is post-series, starting the day Charlie returns from England.

Also, this is the first time i have posted a Numb3rs story where they are adults, so I REALLY hope you like it. (Especially since I got about a half dozen more plot ideas if this one goes well.)

**DISCLAIMER/INTRO:** I hope you enjoy this story that I created, using the characters that are the property of the Scott brothers and their collaborators at CBS, which I do not own nor make money off of. Thank you for reading.

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><p><strong>Chapter 1<strong>

Don ducked under the crime scene tape and gave the room a grim look. The once cluttered office was now a certified mess of papers and blood, with it's owner laying in the middle of it. It looked like a dozen more murders that he had seen over the years, but he knew this one was different. Someone pretty high up on the food chain wanted this solved immediately, otherwise Colby would have handled it and Don would be in bed enjoying the company of his fiancee. Being special agent in charge had it's advantages, such as being able to delegate work more often then not, and disadvantages, such as being called in with the DOD calls your boss who can still delegate when you can't.

"What do we got?" He asked, pulling on a pair of latex gloves.

"Dr. Albert Twersky, PhD's in both electrical engineering and applied physics." Liz answered from her crouched positio nextr to the body. "Night janitor found him like this. Three shots to the chest. No witnesses."

"Any idea what he was working on?"

"No." Colby answered, stepping away from the dismantled computer on the desk. "The hard drive is missing."

"He worked alone, never even let people in his office," Nikki added, "but according to the department head, he had been doing an assignment for the DOD."

That explains the phone call the the assistant director, Don thought to himself, scanning the room for anything that might help them. The papers on the floor looked like nothing more then a years worth of office supply invoices. Squatting down for a better look, the senior agent caught sight of a blood trail leading away from the body. Following it a couple of feet, the blood drops ended a a small cupboard with a red smear on the edge of the door.

"You guys see this?" he called out, opening the door to reveal an empty shelf.

"Yes sir." One of the forensic guys answered. "We are not sure what was in there yet but-"

Don held up his hand, cutting the man off mid sentence. It may have been his imagination, but he could have sworn he heard something.

"Don?" Colby questioned.

"Quiet." Don ordered. "Everyone be quiet."

The room feel silent while Don listened for the sound, and there it was. A soft sound, like someone breathing too fast. He leaned closer to the cupboard and the quiet noise grew louder. He leaned down, sticking his head inside, and came face to face with a small boy.

"Hey buddy." He said gently. "What are you doing in here?"

The shadows of the cupboard made it nearly impossible to see much detail, but those wide eyes shown bright with fear. He was so close that Don could reach out and touch him, but instead he pulled back, gently coaxing the boy toward the opening.

"Come on out, no one is going to hurt you."

Ever so slowly, the boy inched his way to the edge and peered out into the office. His eyes darted from agent to agent as each stayed perfectly still waiting for the boy's next move.

"It's alright." Don assured him. "You can come out."

Sliding to the floor, the boy stood, awkwardly shifting his gaze away from the body. Sensing his discomfort, Don moved so that the kid didn't have to look at the dead man. This also gave him a better angle to look the boy over. He appeared to be around seven or eight years old, with messy, sand colored, hair and bright green eyes. He was dressed in a red and blue stripped shirt, gray tennis shoes, and jeans, all three smeared with blood.

"Hey, my name is Don. What's your name?"

The boy didn't move, but the agent could tell that he had heard him.

"Do you know what happened here?"

This time, the boy looked up to give him a blank stare, fear and sadness filling his emerald eyes. Looks like they had a witness. The sound of movement caught the kid's attention and his gaze drifted over Don's shoulder to where the ME was zipping up the body bag. Walking around the agent, the boy walked over the the black bag, resting his head where the man's chest was. Tears ran down his cheeks as he murmured something to quiet to hear. Pulling back, he took a deep breath and turned away. Don rubbed his hand over his chin and moved closer to the boy.

"Come on, let's go outside."

Reaching out, he gently placed his arm over the kid's shoulders, half expecting him to pull away. Thankfully, that was not the case and he was able to lead him down to where their SUVs were parked, motioning for one of the forensic guys to come with him.

"That was your dad, huh?" He guessed as soon as they were out of ear shot of the other agents.

The boy nodded, scrubbing his eyes with his palm.

"I know how you feel." Don said, pulling open the back door of his SUV and grabbing his gym bag. "My mom died a while back."

He didn't get much of a response, just a brief look of understanding before the kid's attention was pulled to the departing coroner's van.

"Listen," he started, pulled a t-shirt and a pair of draw string shorts from his bag, "I know this is really hard, but I'm gonna need your help to find the people who did this. Okay?"

Nodding, the boy immediately took off his shirt and handed it over to the forensic guy who stood nearby. That was easy, Don thought to himself as he pulled an FBI shirt over his head. The new shirt went halfway to his knees, but the boy didn't seem to mind as he kicked of his shoes and shimmied out of his jeans. Don helped him into the shorts, synching up the drawstring as far as it would go, before sitting him on the back seat of his car.

"You're doing great." He praised. Pulling out swab to get samples of the blood on the boys hands and arms. "Just a few more minutes and we can get you all cleaned up."

He was nearly done scrubbing the rest of the blood off the kid's arms when a small voice surprised him.

"Ari."

"What?" Don looked up.

"My name." The boy said quietly. "It's Ari."

"Okay Ari, did you see what happened?"

"Kinda."

"Can you tell me?"

Ari bit his lower lip, dropping his eyes to the ground. He was scared, a blind man could tell that. What confused Don was that he seemed more afraid of talking then of what happened. But before he could push any farther, he caught sight of the rest of his team waiting for him near the entrance of the building.

"Hey Liz," he motioned her over, "I want you to meet someone. This is Ari."

"Hi Ari." She smiled, squatting down in front of the boy.

"Are you going to get the men who shot my dad." Ari asked, without looking at the agents.

"We're gonna do our best," Don promised for her, "but first I have to go talk to my team. Do you think you can go with Liz and tell her what happened here tonight?"

Again, he saw the flash of apprehension cross the boys face. Ari knew something, something big ... something that he didn't think he could share.

"Maybe …" Ari started slowly, fiddling with the hem of his oversized shirt. "I-I might be able to help … a little."

"That's great buddy." Don encouraged. "Anything you remember will be a big help."

Quietly telling Liz to take Ari back to the office to get his statement, Don turned to meet up with his other agents who were waiting nearby, but stopped when he felt someone grab the back of his jacket. He looked down to see Ari staring up at him.

"What's wrong?"

"Um … I know that … well … they took a piece of Dad's computer, right?"

"Yeah." Don answered, wondering where he going with this.

"Well … what if they went to my house?"

"We'll check there, don't worry about it." Don assured him.

"But what if they wreck our stuff?" Ari questioned, tears forming in his eyes. "What if they wreck my poster or my books? My Dad gave them to me. They are all I have left. I don't want to loose them too."

Don crouched down and looked him in the eye.

"Hey, hey, it's okay." He soothed, rubbing the boy's shoulder in the same way that he used to calm Charlie when they were kids. "I'll make sure that all your things are okay."

"Okay." Ari said softly, turning back to Liz.

"Take care of him." Don ordered, even though he knew he didn't have to.

There was just something about this kid. He had an almost … well, Charlie like quality. It set off the big brother in him and he was more determined then ever to find the people responsible for Ari's pain. One look at his team, who were close enough to hear the boys fears, and he knew he was not the only one who felt that way.

Leaving Nikki to manage the scene, Don and Colby headed to the victim's home address. Luckily. They arrived before anyone else could, not that it was surprising since Dr. Twersky's hole in the wall dwelling was almost literally a hole in the wall. They would have walked right past the front door if an ally cat hadn't tripped Colby. The inside, however, was a far different story. Despite the poor setting, the small apartment had top of the line everything. Flat screen tv, leather furniture, crystal light fixtures, it was obvious this research scientist lived off of more then just his paycheck.

"What do you think?" Colby asked, looking at one of the numerous family photos that were scattered around. "You think the good doctor was up to something dirty?"

"Could be." Don shrugged. "We'll have to get a look at his financials."

The other agent nodded in agreement and walked into one of the two bedrooms.

"Get anything out of the kid?" He called through the open door.

"Nothing yet. I'm hoping Liz might get through to him." Don replied. "He's definitely hiding something."

"Maybe he just needs to talk to someone he knows he can trust. Check this out."

Stepping into the room, Don first thought was that this belonged to Dr. Twersky, but something was off. Alongside of books on physics, math, and geometry were model planes and space shuttles. A solar system hung from the ceiling beside a map of the milky way and a telescope stood in the corner while a stuffed lion sat on the bed.

"You think I should have Larry talk to him?" Don asked, motioning to the area of the room that seemed to be devoted to space.

"Actually," Colby pushed the door closed to reveal a large poster on the back, "I was thinking of someone else."

Jaw dropped, Don stared at the image smiling back at him.

"Charlie?"

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><p>So ... anyone see that coming?<p>

Now, I may not update this one as frequently as my "ABC" story. However, I have been known to be influenced by reviews. The more feedback/requests I get, the sooner I post the next chapter.

Just a reminder, this is my first adult Numb3rs story, so please excuse any minor flaws.


	2. Chapter 2

I'm glad people seemed interested in this story. (I actually made it up years ago, but this is the first time I was brave enough to post it.)

So, I am following a format from my supernatural stories and alternating between the two brother's POV. (I hope this doesn't confuse anyone.)

Enjoy ...

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><p><strong>Chapter 2<strong>

Charlie followed dad into the craftsman then headed straight for the couch. First class or not, that flight had been the longest eleven hours of his life. At least Amita had managed to sleep through most of it. Flopping face first into the cushions, he breathed in the smell of home. London had been great, especially the part of having so much alone time with his wife, but it would never compare to Pasadena.

"If you're that tired, maybe you should head up to bed." Alan's voiced called from somewhere nearby.

"I'm fine." Charlie said into the pillow.

"Well, I'm not," Amita sighed. "I'm am going to take a hot bath and go to bed."

"Not too hot." Charlie reminded her, turning his head to give her a knowing look.

She just smiled, their secret shining in his eyes, and nodded. As she slipped up the stairs, Charlie caught his father's gaze.

"Not too hot, huh?"

"She hasn't been feeling too well." Charlie replied dismissively. "Don't want her passing out in the tub."

"I see." Alan murmured and went to help Larry bring in the rest of their luggage.

Once he was out of sight, Charlie let out a sigh of relief. That was too close. But he had to quickly pull himself together, because at that moment Alan came back in followed by Larry and Don.

"Hey Charlie." Don grinned, setting a couple of bags down. "How was London."

"Great." He answered, getting too his feet.

His family was never very big on hugging, but after not seeing his brother for six months, they could make an exception. The embrace was brief, but strong. It was official, he was home.

"So," Charlie clapped his brother on the shoulder. "How's work been going? I heard you lost your replacement equation monkey to MIT."

"Yeah …" Don replied slowly. "That's actually why I'm here."

"Donnie," Alan scolded, "he's been home five minutes. Give him a chance to get settled."

"It's fine, Dad." Charlie assured him.

Actually, he was eager to get back in the saddle. Six months of nothing but teaching, even if it is in London, reminded him how much he enjoyed helping people. And, it turned out, Scotland Yard was not as open minded about using math as the FBI was. Go figure. But before Don could answer, the door swung open and Colby came in dragging a giant suitcase.

"Hey Charlie." He grunted, dropping the thing by the wall. "What did you pack in here? The tower of London?"

"No, that's in our other bag." Charlie laughed and gave his friend a quick hug.

"So did you ask him?" Colby questioned his boss.

"I was just about to." Don answered, before turning to Charlie and Larry. "Have either of you heard of Dr. Albert Twersky?"

Charlie thought for a moment. The name definitely sounded familiar. Wait, he had herd of Dr. Twersky. He was the founder of a group that had visited CalSci a few years ago to make sure their labs were safe.

"Yeah, I have." He told his brother. "He started a campaign to increase safety measures in research labs."

"Yes, that's right." Larry nodded. "That was after his wife died. I met him shortly after at a string theory conference."

"Yeah, well, he was killed tonight." Don stated.

"Oh dear." Larry murmured.

Charlie clasped his hand on his friend's shoulder in support. He remembered now, after Larry got back from his string theory conference a few years back. He had told him about meeting Dr. Twersky, about how jittery and nervous he seemed around people, but was so passionate about his work. Even though he had never got the chance to meet the man himself, he still felt the loss for the academic community.

"What happened?" Charlie wondered.

"Someone broke into his office and shot him." Colby answered. "We think whoever did it also stole his files and hard drive."

"Oh, that is not optimal." Larry murmured.

"Do you know what he was working on?" Don questioned.

"Albert was latest in a long line of brilliant scientists, going from the discovery of radium to nuclear warfare." Larry explained. "From what little he told me about his work, I think it is safe to assume that whatever he was developing now will have massive repercussions."

"That's what we were afraid of." Colby said grimly.

Suddenly, Charlie started wondering if it would better to send Amita back to London for a little while, maybe bring his dad with her. Then again, if Larry was right, he wasn't sure if there was anywhere that his family would be safe until they caught the killer and stopped them from using whatever they stole.

"Do you have any leads?" He asked.

"One," Don replied. "We think Twersky's son might have seen something, but he won't say much."

"I wasn't aware Albert had children." Larry frowned. "Granted, the man had just lost his wife, so family must have been a touchy subject, but he never mentioned any."

"Well, the kid says he's his son." Don shrugged and turned to Charlie. "I was hoping for might try talking to him."

Charlie blinked at his brother in surprise.

"Me? Why me?"

The agents shared a look and Colby picked up a large roll of paper. He gripped one end, letting the rest drop to reveal a poster … of him! He recognized the picture as a promo shot for one of the magazines he did after his book came out, and the quote 'everything is numbers' was one he had said often enough, but why in the world would someone want a poster of a mathmatician?

"Oh wow." Alan exclaimed, coming back in the room. "I didn't know they made those."

"Neither did I." Charlie gaped.

Reaching out, he took the poster from Colby's hands to get a closer look. It had the look and feel of a store bought poster … but it was him! He was still trying to wrap his brain around this, when his robe clad wife came down the stairs.

"Charlie, have you sen my- oh!" She smiled and gave her brother-in-law a hug. "Hi Don, Colby. I'm sorry I didn't know you were here."

"They came about a case." Charlie mumbled, looking back at the poster in his hands.

"What's that?" She asked, peering over his shoulder.

"A poster of me."

"It belongs to a boy named Ari." Don explained. "His father was killed tonight."

"Albert Twersky." Larry added.

"Twersky?" Amita paused. "Wasn't he the one with the crusade for safety?"

"Okay," Colby interjected, "what is this safety thing you guys keep talking about?"

Still trying to get over the fact someone made a poster of HIM, Charlie let Larry take over the explanation on that one.

"Four years ago, Albert's wife, Emmy, died after being exposed to dangerous chemicals. The incident was caused by lax safety measures and Albert made it his mission in life to make sure that what happened to her never happened to anyone else."

"He traveled all over the country, visiting labs and research facilities." Amita added. "He made sure new protocols were put in place to prevent other accidents."

"Did he make any enemies doing this?" Don asked.

"No," Charlie shook his head, handing the poster back to Colby. "Most places were more then willing to install the preventive measures, as much to protect their scientists as themselves. The lawsuit that resulted from Emmy Twersky's death alone cost the lab she worked at millions."

"Explains his apartment." Colby muttered.

He handed the poster over to Alan, who was studying it curiously.

"You know, this reminds me of when Don was twelve and got a poster of Wayne Gretzky. Charlie thought it was so cool that he wanted one too. But when we went to the store, he demanded that we buy him Albert Einstein."

"Yeah, but they actually sold posters of Einstein." Charlie pointed out.

"And apparently they sell posters of you too." Alan pointed out.

Uncomfortable at the thought, Charlie sent Don a pleading look. For once, his older brother seemed to have pity on him a changed the subject … kinda.

"Well, the kid who owns this is our only witness, and I was hoping you could talk to him."

"Sure."

Anything to get that poster out of his dad's hands before he got any ideas about making copies.

"You might want to come too, Larry." Don added. "He probably knows your work as well."

Soon, the four of them were exiting the elevator and entering the bull pen. Charlie looked around, wondering where the kid was. He spotted him in one of the conference rooms sitting with Liz. Ari shoulders were slumped in a way that made him look almost tiny. His gaze was downcast as he pushed a can of coke back and forth between his small hands. Even from the distance, he could see a tear trickle down the boy's cheek before he quickly wiped it away, and suddenly Charlie wasn't sure he could do this. He knew how crippling loss could be, how broken he was when his mom died, but at least he still had family and friends to support him. Now that Albert was gone, Ari was alone in the world. But then he caught the look on his brother's face, and knew that he was wrong. He had an entire FBI team in his corner, and they were going to get justice for his murdered father.

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><p>This might be a stupid question, but does anyone feel sorry for the killer(s) when Don amd his team get hold of them?<p>

Again, let you know what you think and I will get started on the next chapter ... of something ... let me know if you want it to be this one. (It may be the "ABC" story or one of my others. Not sure yet.)


	3. Chapter 3

Just a quick note, when I wrote the last chapter I must have been sleep deprived or something. For some reason I could have sworn the words "London" and "England" were interchangeable. (And yes, I am a college student.) Sorry if there was any confusion and thank you to the reviewer who pointed out the error.

Anyway, on with the story ...

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><p><strong>Chapter 3<strong>

Don led the way into the conference room, sharing a brief look with Liz as she silently told him that she didn't have anything new to report. He gave her a slight nod and turned his attention to the boy.

"Hey Ari," Don said gently, "there's someone I want you to meet."

He looked up, his eyes widening as Charlie stepped into the room. The mathematician gave him an awkward smile and took a seat at the table, followed by Larry.

"Hi, Ari. I'm Charlie."

"I know," he said quietly, "I've read your work."

"You mean my book or my papers?"

"Both. The papers were better."

"I thought so too." Charlie chuckled, but sobered quickly. "I'm really sorry to hear about your dad."

Ari dropped his gaze back to his soda, wiping his face with his sleeve. For a minute, Don was afraid he was going to clam up again and took half a step forward, but stopped when the boy looked up.

"Are you going to help them find the killers?"

"I'll do my best." Charlie answered sincerely.

"Are you going to help too, Professor Fleinhart?" Ari asked, leaning around to see Larry.

"I'll do whatever I can."

"Here's the thing," Charlie started hesitantly, glancing from Don to the boy, "in order to find the killers we need to know anything you can tall us about what happened."

"Um … okay." Ari said slowly. "But first, can I ask you a question?"

Charlie gave him a puzzled look and nodded.

"Yeah, you can ask me anything."

"What is your security clearance level?"

At this point, Charlie looked beyond confused, and he wasn't the only one.

"Why do you want to know that?" Liz questioned.

"So I can know what he can know." Ari replied, as if the answer was obvious. "Dad's work was top top secret. I can't just talk about it to anyone."

Now it was Don's turn to intervene. He squatted down by Ari's chair and looked him in the eye.

"Are you telling us that you know what it was that they stole."

The boy bit his lower lip, dropping his eyes toward the floor. Though he stayed silent, his answer was loud and clear. And if he did know what the doctor had been killed over, he might be more then a witness. He might be a target.

"What was he working on?" Charlie asked quietly.

"I can't tell you until I know if you are allowed to know."

"Trust me," Colby assured him, "we're allowed to know."

The kid didn't look convinced and turned his attention back to his soda can. This was getting them nowhere. Clearly Twersky had taught his son the importance of security clearance, but somehow they had to convince him that they needed to know whether their clearance was high enough or not.

"Ari," Don said seriously, "if we are going to find the killers, we need to know what he was working on."

"Okay." The boys said hesitantly. "I'll tell you the secret stuff and if you need to know more I can probably tell you the top secret stuff, but I can't tell you the top top secret stuff. Not even the men from the government know about that."

At this point, Don was more than curious about what the late doctor was working on and how the killers had found out about it. First things first.

"Okay," he nodded for Ari to continue, "what's the secret stuff?"

"Dad was working on a project for the DOD involving missiles."

Yeah, they were DIFINITELY going to need to know more then that.

"What's the top secret stuff?" Colby questioned.

Once again, Ari bit his lip, but Charlie reached out and put a supporting hand on his shoulder.

"It's okay, you can tell us."

For a moment, Don felt like he was looking in a mirror. The support Charlie was giving there kid was reminiscent of how Don handled many of the early school bullies. Of course, that was when they were at another school and it was harder for him to bust their face in. Then their was the look of absolute trust that Ari was giving his little brother. If it wasn't for the sandy hair and green eyes, he could very well have been his little brother. But the moment ended abruptly when Ari opened his mouth.

"Dad built a remote control system for missiles. Attach it to one and you can land on a moving dime twenty miles away."

"And when you say built …" Colby said slowly.

Ari turned to him and nodded.

"He finished it this morning."

The silence in the room was defining, but lasted only for a second before Don took control.

"Liz, get on the phone with ATF, see if they know of any weapon shipments that these guys could use. Colby, you and Nikki take the office building. I want to know how these guys knew when to move and how they got in. Charlie, you and Larry stay here with Ari. I have to go talk to the assistant director."

He and his agents left the room, splitting up once they past the door. Don headed straight for his office. Even after six months, he was still getting used to not being in the bull pen with everyone else, but at time like this, he liked the privacy. Waking up the assistant director of the LA office to tell them that you may have another 9/11 on your hands wasn't exactly something you wanted to do with an audience. On a side note, he might want to call Robin too, since it was likely he wasn't going to be heading home any time soon. Glancing at the photo of her he kept on his desk, he started dialing his home number. After all, a five minute delay was not going to chance the assistant director's mood.

"Hello?"

Just the sound of her sleepy voice was enough to bring a small smile to his face.

"Hey."

"Hey yourself." She replied, sounding more awake. "So, I assume since you are calling that you will not be coming home tonight?"

She knew him so well.

"Big case. Not sure when I'll be home."

"Anything I can do?"

"I'll let you know when we get a suspect."

"Okay." She yawned. "If your not hear in the morning, I'll bring you somethig on my way to work."

"It's a date." He smiled. "Goodnight."

"Night."

He hung up and had just started to dial the assistant director when his brother went running past his door. Looks like it was going to be a ten minute delay before he made his phone call.

"Charles." Larry called after him, rushing into Don's office with Ari in tow.

A few seconds later, Charlie came skidding inside panting for breath.

"Have you made the call yet?" He asked.

"No, why?" Don looked at each of them in turn. "What's going on?"

Charlie took a seat into one of the chairs facing his desk while Larry ushered Ari into the other.

"They didn't get it."

Don rubbed a weary hand over his eyes. As much as he loved and missed his brother, there were certain things he didn't. His cryptic messages for example.

"Who didn't get what, Charlie?"

"The killers. They didn't get what they were looking for."

That was more like it. He leaned forward, glancing at the little boy before turning back to his brother.

"You mean the program wasn't on the hard drive?"

"No," Ari shook his head, "it was."

"So, they didn't get the hard drive?"

"No, they did." Charlie answered.

Don shook his head, trying to make sense of this whole thing.

"So … what?"

Surprisingly, it was Larry who managed to give him a straight answer.

"Albert was so aware of the threat his work posed that he went to extream lengths to ensure it never fell into the wrong hands?"

"Okay … so, what does that mean?"

He had been looking at Larry, but it was Charlie and Ari who leaned forward.

"Imagine a clock with all the gears removed." Charlie started. "It's still a clock, but it's not gonna tell you what time it is."

"Exactly." Ari nodded "Dad finished a program, but he deleted key codes and algorithms, wiping them from his system. The only have a shell of what they are looking for."

Well, this was the first good news he had got in a while, but following Charlie's analogy, even a broken clock was right twice a day. If the data existed, there was still a chance that the killers could find it.

"So, where is the rest of the program?"

Based on the looks on their faces, they had already given him all the good news he was gonna get.

"Um …" Charlie said slowly, "that would be the top top secret stuff."

Of course it was. Don sighed inwardly, rubbing his hand across his face.

"It's really safe." Ari assured him timidly. "I just … I made a promise not to tell."

"The thing is," Don said seriously, looking the boy in the eye, "if I don't know where it is, then I can't protect it."

Ari dropped his gaze, fidgeting in his seat.

"I'm sorry … but I … I just can't tell you."

He got up suddenly. running from the room with Charlie at his heels. Larry sighed and shook his head.

"We'll talk to him, but I'm not sure if it will change anything."

"Do what you can."

Larry gave him half a smile and left the room. Don sighed and picked up the phone. This was going to be a really long night.

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><p>Looks like Don has his work cut out for him. What do you think?<p>

Let me know and I will get started on the next chapter of this and any others that get requested. :)


	4. Chapter 4

Sorry for the wait. Real life can be a real pain sometimes.

BTW, sorry for any mistakes. I currently have no beta and have a really bad habit of writing when I am not fully awake.

Anyway, enjoy ...**  
><strong>

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><p><strong>Chapter 3<strong>

Charlie followed Ari back to the conference room, where he found the boy sitting in the corner with his knees pulled up to his chest. His face was buried in his arms and his small shoulders shook with quiet sobs. For a second he saw himself in the days after his mother died, remembering the moments when not even the math could bury his grief. He took a deep breath to control his emotions, and push back the memories, before taking a seat one the floor next to Ari. He didn't know what to say, or even if there was anything he could say, so he just placed his arm around the boy's shoulders and just tried to be there for him.

"W-why did th-ey do it-t?" Ari cried, tears streaming down his cheeks. "He-he d-did every-th-thing they s-said. W-hy di-id they have to sh-shoo-shoot my d-ad?"

Charlie looked into those sorrow filled eyes and wondered how Don, or anyone for that matter, could handle the victims of this job. What do you say to a child who watched his father die? How do you explain to that little boy why he's an orphan? How do you rationalize evil?

"Nothing is easier than to denounce the evildoer; nothing is more difficult than to understand him."

Shooting Larry a grateful glance as he came farther into the room, he turned back to the boy.

"I don't know why they did what they did, but I do know that we will do everything we can to keep them from hurting anyone else."

Ari wiped his face with the hem of his oversized t-shirt.

"D-do you think …" he sniffed, his tears finally slowing."Do you think they'll get them?"

Charlie paused, wondering how to answer. With very little to go on and a infinite list of suspects, he knew the chances were not great. Then again, he also knew his brother. Don wouldn't stop until he got these guys, no matter how long it took him.

"Yeah, I do." Charlie gave him a reassuring smile. "Don's got one of the best clearance rates in the country."

"It's not high enough for me to tell him where the key to Dad's program is."

"Well, I was actually referring to the clearance rate for closing his cases but I'm sure he has a high enough clearance."

"There is also the the chance that either Charlie or I have a high enough clearance level to be in your confidence." Larry added.

"You don't understand. It doesn't matter how high your clearance level is. Okay … maybe for some stuff it is, but I already told you about that stuff." Ari sighed and shook his head. "Let me put it this way; if the head of the CIA asked me to tell him, I wouldn't. If the Secretary of Defense asked me to tell, I wouldn't. If an act of Congress ordered me to tell, I would probably go to jail before I told them anything. If the President of the United States himself asked for the information …. well, then I MIGHT tell, but I think you get the point."

Charlie got the point all right. Looks like Albert taught his son the old saying about how three people could keep a secret if two of them were dead. Sadly for them, it had become a reality.

"So no one else knows where the information is?" Larry questioned.

"Nope." Ari shook his head. "Dad didn't trust anyone else enough."

Looks like there was good reason for that, Charlie thought to himself. But this posed a problem. If the killers found out that Ari was their only link to a working prototype they would do everything in their power to make him talk. Now he was no criminal mastermind, but he had seen enough crime scene photos to know that Ari's body would give out long before his willpower. He had to find Don. Pushing himself to his feet, he whispered to Larry to keep an eye on the boy before heading back to his brother's office.

"Charlie?"

"Yeah?" He paused halfway through to door and turned to look at Ari.

"Um … do you know a Rabbi?"

To say he was startled by the question was a bit of an understatement. He glanced at Larry, but his friend just shrugged.

"Why would you ask that?"

"Well … you're Jewish, aren't you?"

"Um … yes, but … I'm not very religious." Charlie admitted, moving back into the room. "The last Rabbi I talked to was at my mom's funeral."

"Did he do a good job?"

Okay, not these questions were getting really off topic. But then again, Ari didn't seem like to type for idle chit-chat in such a serious situation.

"Why do you want to know?"

Ari dropped his eyes, tuging a loose string on the hem of his shirt.

"It's just … Dad was Jewish." He whispered. "He didn't go to temple that much, but … he'd want to be buried like one."

"Oh." Charlie nodded in understanding. "Well, I'm sorry, but I don't really know any Rabbis. You would have to talk to Don."

"Is Don Jewish?"

"Don is my brother."

Ari looked up in surprise. Apparently, Don had left that little detail out when he had brought hm here. Not that it was too shocking. He didn't really like to introduce himself as the special agent brother of Dr. Charles Eppes.

"You have a brother?"

"Yes, an older brother."

"Wow." Ari looked back at his hem. "I guess the term 'big brother is watching' takes on a whole new meaning for you, huh?"

Despite the situation, Charlie had to laugh. It was true though, 'big brother' really was his big brother. Speaking of which, he really had to talk to him.

"Yeah," he chuckled. "Stay with Larry. I'll be right back."

He headed down the hall, trying to retrace his steps. Don hadn't taken his promotion until after he left for Cambridge. He was glad that they had finally recognized his brother's contribution enough to give him an office, he just wished it was easier to find. Once again, he walked right past it before Don called him back.

"Get anything out of Ari?" He asked, pulling some papers out of his fax.

"A little."

Don muttered a response, looking over the papers before shoving them in a folder and setting it aside. Charlie gave the folder a curious glance as he took his seat. His brother was an SAC now and had a lot more to oversee then just this case, and until classes started up Charlie didn't have much on his plate besides this case.

"What's that?"

"Nothing much." Don answered dismissively. "Now, what did Ari tell you."

"To sum up, he is the only one who knows where Albert hid the codes and the only person he MIGHT tell is the President." He paused, his gaze falling back on the folder. "You sure you don't need my help with that, because I would be more then happy too-"

"Forget about that, Charlie." Don snapped. "Now, is there anyway you can get him to trust us with the information?"

"Not that I can see."

At least, not without an inaugural address, he thought to himself. But his big brother was clearly not in the mood for that kind of comment. In fact Don looked exhausted and Charlie couldn't help but wonder how many hours he had put in that day.

"Alright." Don sighed, rubbing his hand across his mouth. "Thanks for your help. Why don't you go get some sleep."

"What about you?"

"Don't worry about me," Don gave him half a smile, "I've pulled all nighters before."

"Yes," Charlie smirked back, "but you were younger then."

"Out." Don ordered, though he couldn't keep back his grin.

Charlie held up his hands in surrender and was almost to the door when a thought struck him.

"What's gonna happen to Ari?"

"We're gonna track down a relative." Don replied, going back to his paperwork. "Until then, child services takes care of him.

He had been afraid he would say that. Charlie deep breath, hoping that he would get a better answer to his next question.

"And if you can't find any?"

"He stays in the system."

Charlie nodded and turned away, having no intention of leaving yet. He had to get a hold of child services. Don would probably take care of it, or at least have one of his agents do it, but child Services wasn't going to find relatives and foster care was just not a good place for someone like Ari. It would put out his light before he ever got the chance to shine.

* * *

><p>Anyone have any ideas on what should happen to Ari?<p>

Let me know what you think and I will get started on the next chapter.


	5. Chapter 5

Hello all. Looks what else I'm working on again. :)

So, I was a bit stuck on this story and how I was going to have it play out until the fabulous Lalene Brooks offered her insight and beta services to get it back on track. (You're awesome.)

Anyway, here is what happens next ...

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><p><strong>Chapter 5<strong>

Don wearily rubbed his eyes, reluctantly glancing at the clock. So much for getting any sleep. Larry had brought Ari by shortly after Charlie left. The boy was sound asleep, curled up on the same couch that Don usually napped on during these all nighters. Of course, with the security level of this case, he had been too busy to even think about resting. He had already declined offers to take over the investigation from just about every federal agency in the country. It appeared that Dr. Twersky had worked with everyone from the pentagon to the post office. He even had to deal with a couple of private contractors who were concerned that the murder had to do with one of their projects that Twersky had consulted on, as if he needed more leads to check out.

Currently, their best bet was the DOD project he had just finished, but Don knew that they couldn't ignore other possibilities and assigned agents to each new tip that came in. Interestingly enough, not one of the agencies or contractors knew anything about Ari. It was as if the kid didn't exist.

"Don?"

The SAC looked up and quietly waved Liz into the room, motioning to the sleeping boy on the couch. The agent tip-toed into the room and placed a file on his desk.

"Here's the information you asked for." She whispered. "Barring any discrepancies in the DNA test, he checks out."

Don nodded in thanks and picked up the file as Liz slipped out. He felt a little bad running a check on a victim, especially one so young, but it was protocol. Beside he couldn't understand why Twersky kept him tucked away like he did.

"What were you afraid of?" Don murmured to himself, looking over Ari's birth certificate.

"What was who afraid of?"

His head snapped up and he gave a small smile to the sleepy boy on the couch. Inconspicuously tucking the file under a small stack of others that looked just like it, Don rose and walked over to Ari, crouching down so they were at eye level.

"Hey, how'd you sleep?"

"Okay, I guess," he shrugged. "How about you?"

"That's assuming he actually slept."

Don looked up to grin at the most beautiful woman he had ever seen, and she brought him doughnuts.

"Hey Robin," he rose to give her a kiss, before turning back to the boy. "Ari this is my fiancée. Robin, this is Ari."

"Hello Ari," she said warmly, opening the box she was holding. "Want one?"

"Yes please."

"Aren't you a polite one," Robin commented, placing one of the treats on a napkin for the little boy.

"Mom always said, 'whoever one is, and wherever one is, one is always in the wrong if one is rude'." Ari quoted. "Of course, Maurice Baring said it first."

"Hey," Don cut in, taking the box from Robin and holding it out to Ari, "do you think you can take these into the break room for the other agents?"

Mouth full of maple bar, the boy nodded and carried the box out of sight. Once he was gone, Don turned back to Robin.

"Thanks for breakfast."

"Glad I could help."

"Well … there something else I could use your help with."

"Ari?"

She knew him so well. Don nodded, pulling the folder out from the bottom of the stack. So much information, but they still knew nothing about him. But that wasn't want he needed Robin for.

"He's not only a murder witness, but he is the only lead we have on what his dad was working on."

"Sounds like you should put in a call to the US Marshals. I think that's more their department."

Yeah, Don thought bitterly, that same people who got his ex-girlfriend killed. No thanks. Lucky for him, being SAC had its perks.

"I'm keeping him in FBI protection for now," he stated. "No, what I am worried about is after that. Normally, a kid in his position would go into foster care, and there's not much I can do about it. But, he also knows a lot of top secret information."

"So, you want me to pull some strings to keep him from getting lost in the system?"

"Well, yeah, I mean he's-"

"Say no more," she smiled. "I'll see what I can do."

With one last kiss, and a reminder that he had promised to be at Charlie's house for dinner, Robin stepped out. Don had barely had a chance to sit down before Ari came back in, setting a large cup of coffee and a doughnut on the desk in front of him. He was really starting to like this kid.

"You forgot to grab one," the little boy explained. "I hope you like sprinkles."

"Yeah, thanks buddy."

He took a sip of the steaming hot brew, declining the cream and sugar packets Ari offered before taking a seat on the couch.

Two faxes and one case update later, he was still sitting there. Don was thinking about where he could put him that would be safe but not quite as boring for an eight-year-old as an FBI office when a small voice interrupted his thoughts.

"Do you know a good rabbi?"

"What?"

"A rabbi, for my dad's funeral."

"Oh, yeah, sure. I can help you with that if you want, but my dad could probably help too."

"Okay."

Ari fell silent again as he sat looking at his hands. The kid was clearly trying to be brave, but Don had seen too much not to notice the fear and pain in his eyes. Under all the secrets Ari was carrying he was just a scared little boy orphaned by an act of violence, which made Don even more determined to catch the guys who killed Dr. Twersky.

"Hey, Ari, how would you like to get out of here?"

"Can I? I-I mean … is it safe?"

"Yeah, of course it is," Don keeled down in front of the boy. "I'm not gonna let anything else happen to you. Alright?"

"Alright. Are you coming with me?"

"Not just yet, I got a lot of work to do, but I will be by later. That okay?"

"I guess it's adequate."

Don almost laughed at the word choice as he stood up. He almost forgot how Charlie would throw out these words his teachers and tutors would use around him, no matter how weird it was. Ari was definitely becoming a blond haired clone of his brother, but that only confirmed what he already suspected about moving him. Leaning out his door, he was glad to see Colby was back from the office building. Once he gave his report he would go on body guard duty and maybe, just maybe, he might be able to get through to Ari. After all, who knew what secrets a mind like that held.

"Sir?"

Don looked up to see one of his junior agents standing in the door and waved them in, hoping that they were bringing him updates and not another lead to track down. Ari had only been gone five minutes, but his work load seemed to have doubled since the kid left. Maybe he should have gone with him after all …

"What is it Keller?"

"Two agents from the DOD are here. They want to speak with you."

Don rubbed his hand over his face and let out a frustrated sigh. He had already spent twenty minutes on the phone with the DOD, mostly reiterating that he fully intended to take care of the investigation himself.

"Did they bring information?" the SAC questioned.

"Not that I'm aware of, sir."

This doesn't bode well, Don thought to himself. Still, he better see what the guys wanted. Maybe telling them no in person would be more effective. Following Keller past the war room, Don found two suits sitting in one of their conference rooms looking very annoyed. He dismissed his junior agent and took a seat across from the men.

"What can I do for you gentlemen?" Don asked, choosing to play the diplomatic role for now.

"We understand that Dr. Twersky's killers did not get a complete copy of his work," one of the men started.

"No, they only got a rough outline of the program," Don confirmed. "My people assure me that it's highly unlikely the killers will be able to do anything with it."

"By your people, you mean your brother," the other man stated bluntly.

"What? Are you saying you have a problem with him working the case?"

He allowed a defensive edge to creep into his voice, making it clear that he was not pulling Charlie off this case. He just got his brother back and there was no way the DOD was taking that away from him. The other agents seemed to get the message and the first one raised his hand slightly in a calming manner.

"We have no problem with Professor Eppes working this case."

"Then why bring him up?" Don demanded.

"We understand that he got his information from your witness; Twersky's son."

"So?"

"We need to speak to the boy," the second agent replied.

"Not gonna happen," Don shook his head. "He's a witness in a murder investigation."

"Agent Eppes," the first one, and obvious good cop, started. "We have reason to believe that Dr. Twersky gave his son information that may prove to be detrimental to national security. We need to talk to him to see how much he knows."

His words may have seemed innocent, but his partner's tone gave away intent. They didn't want to just talk to Ari, they wanted to interrogate him. If they got their hands on him, Don had no doubt they would use any means necessary to make him tell them his father's secrets. Standing up, he looked down at the other agents.

"We're done here."

He turned to leave, but the bad-cop agent grabbed his arm. He turned to face him and the two locked eyes as Don dared the other to try something. Out of his peripheral vision, he could see agents pausing to watch, waiting on an instruction from their SAC. This wasn't the DOD, these guys were in Don's house and he was not about to be pushed around.

"Wilson," the good-cop agent cautioned, pulling his partner back. "Stand down."

"We will talk to the boy, Agent Eppes." Wilson warned.

"Yeah," Don replied. "On a cold day in Hell."

He turned and headed back to his office, trusting his own agents to get the DOD scum out of his building. Sitting down at his desk, he immediately picked up his phone to call Robin. It wasn't just the killers after Ari anymore; now they had to find a way to protect him from their own side.

* * *

><p>Looks like trouble for young Ari. Can Don protect him from ... well ... everyone?<p>

Let me know what you think while I get the next chapter (and the final chapter of "The ABC's of Numb3rs") sent off to my wonderful betas. :)


	6. Chapter 6

Hello again!

A word of advice, try not to time your vacations so you get back only a few days before a new term starts at school. (It kinda makes you head spin for a day or two, give or take a week.)

Anyway, this chapter is a bit short because I honestly couldn't figure out where to make it longer.

A big thanks to Lalene Brooks for her beta work and support.

Enjoy ...

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><p><strong>Chapter 6<strong>

Colby pulled up to the craftsman, making note of the second SUV parking across the street. Until they found the killers, Don wasn't taking any chances with this kid's safety.

"Those are your guys, right?"

This very observant kid's safety.

"I hope you like babysitters," he commented, climbing out of the car.

Doing one last perimeter scan, Colby led the way up to the porch, his hand causally draped across Ari's shoulders. This wasn't his first body guard assignment, but this was the youngest charge he had ever had and nothing was going to happen to the boy on his watch. Satisfied that the area was clear, he knocked.

"Hey, Colby," Alan greeted, opening the front door. "Come on in."

"Don tell you we were coming?" the agent asked, ushering Ari inside and closing the door behind him.

"Yeah, and he said to have you call him back."

"Thanks," Colby replied, before looking down at his charge. "Ari this is Alan, he's Don and Charlie's dad."

"Hello Ari," Alan smiled. "You hungry."

"I had a doughnut."

"That's hardly breakfast."

"It's what Don had."

"Oh really," the father raised an eyebrow. "Well, why don't we see if we can't find you something better."

With a quick glance at Colby, who gave his nod of approval, Alan ushered the boy into the kitchen. Taking advantage of the distraction, the agent flipped out his phone and called his boss. It only took two rings before he got an answer.

"Eppes."

"Hey Don, your dad told me to call."

"Yeah. The DOD was just here. They want to talk to Ari."

"And by talk to you mean interrogate," Colby responded grimly.

He glanced back at the kitchen, as if he could see the boy on the other side. The DOD wasn't known for their tact and sensitivity. Any interaction with them would probably cause Ari to shut down even more, which was the last thing they needed. Lucky for Colby, his boss agreed.

"Well, that's not going to happen. Robin is already doing what she can to keep him in FBI protection, at least for the duration of the case."

"What about after?"

"You let me worry about that. For now, though, I don't want anyone getting near Ari without my direct permission."

"Got it. I'll pass word on to the team outside."

"You do that," Don said, pausing for a moment. "How's he doing?"

"Your dad's getting him breakfast."

"Good. I should be there sometime this afternoon. Just keep an eye out and let me know if he opens up about anything."

"Will do."

Colby hung up just as Alan and Ari emerged from the kitchen, the smaller one carrying a stack of plates while the other held a pan of scrambled eggs and bacon. He knew there was a reason he liked working security at the craftsman.

After breakfast, Ari settled down with a book while Alan did the dishes and Charlie and Amita went to a meeting at CalSci. Knowing he needed to stick with Ari, and not really in the mood to read, Colby tried instead to find something good on daytime tv. For lack of a better option, he settled on a game show. Of course watching housewives win blenders could only do so much to keep one entertained. In fact, after only a coupe of minutes, he found Ari and his book far more interesting.

"What are you reading?"

"The Great Physicists from Galileo to Einstein."

"Sounds like a real page tuner."

"It was my dad's."

Colby fell silent, mentally kicking himself for reminding the kid what he lost. He turned back to the tv in time to see the prize girls unveil a new car and fought the urge to zone out. It was times like this he wished David had never transferred to Washington. Of course, he was thrilled that his friend had been recognized and put in such a great position, but the waiting game wasn't as much fun without the banter of a partner.

"Are you okay, Colby?"

"I'm fine," he replied, giving the concerned little boy a smile. "I was just thinking about a friend of mine."

"Did he die?"

"No, David just moved away. What about you? Do you have any friends?"

"A few colleges of my parents," Ari shrugged, closing the book. "I wouldn't really count them as friends though. I don't know them very well."

Suddenly much more interested in his conversation than who won the car, Colby switched the tv off and turned towards Ari. If Dr. Twersky had colleges there was a possibility that one of them might have an idea what he was up too, maybe even be the leak that got him killed.

"Had he talked to any lately?"

"Um …" Ari bit his lib, his face calculating. "I think he met with a couple in the last week or so, I'm not sure though. Why? Do you think … do you think they helped kill my dad?"

"Well, we have to check out all the options. Do you think any of them might have known where your dad hid the codes?"

"No," Ari stated firmly, shaking his head. "He would never trust anyone with that."

"Except you."

Ari dropped his gaze, fingering the corner of his book, and Colby moved to sit next to him. He wasn't sure how much he could do, the kid wouldn't even open up to Charlie. Still, there was one thing they had in common and, if Colby played his cards right, it just might lead to finding out where Twersky's codes were hidden.

"You know, a few years back, I got arrested for keeping a secret."

"Really?"

"Yeah. I was caught passing secrets to the Chinese, but what I was really doing was spying on the spies to find a leak in the DOJ. Only my handler knew what was really going on."

"So what did you do?" Ari asked, looking up at him with wide green eyes.

"Not much I could do without blowing the whole case," Colby shrugged. "But after I lost touch with my handler, I knew I was in trouble."

"Did you blow your case?"

"Nope, I just called the one person I knew, one hundred percent, that I could trust. I told him what was going on and he managed to save my life and catch all the bad guys. Do you know who that guy was?"

"David?"

Colby gave the boy a sad smile at the memory. His best friend had felt betrayed and angry, not someone who was ready to believe a single word that came out of his mouth. They managed to get their friendship back on track, but at the time he went to someone else.

"No; it was Don."

If Ari was surprised by the answer, he didn't show it. He just looked down at his book, thoughtfully running his finger along the binding. Colby couldn't help but wonder what was going through his mind, or more importantly if he was getting through to him. One thing he did know was, if those killers found the codes before they did, no place would be safe.

A couple hours later he was standing in the backyard watching Ari feed the koi. The kid had barely said a word since their talk and Colby was starting to get worried that he had made things worse instead of better. Movement in the house caught his attention and he looked over to see Charlie bringing out a couple of sodas.

"Any luck?" the professor asked quietly, holding out one of the cans.

"Nope," Colby sighed, accepting the drink.

"Mind if I try?"

Colby gestured his friend to give it a go and Charlie approached the boy and took a seat in the grass next to him. Ari didn't react with anything more than a quick glance, leaving Charlie to sit in awkward silence for a few seconds before he held out the second can.

"I brought you something to drink."

"Thank you," Ari responded in a voice just above a whisper.

He took the soda and set it on the ground, then tossed a handful of food into the pond. Charlie followed his gaze and relaxed, absorbed into the movements of the koi. It was almost unbelievable how long the silence lasted as they watched them swim around the small pond. What was with these smart people and fish?

"When is Don coming?" Ari asked suddenly.

"Oh, um," Charlie glanced at his watch. "A couple hours, maybe. Why?"

"No real reason," Ari shrugged. "I like it when he's around."

"Yeah, me too."

And with that the two were once again lost to the world of the koi. There was no awkwardness this time, just companionable silence. Colby was starting to wonder if the water put people of a certain intelligence under some kind of trance when Charlie pointed across the water.

"You know, each koi has it's own unique path that you can see if you watch them long enough."

"I've heard that," Ari replied. "How long do you have to watch them to find it?"

"Oh, it took me months to chart each one, but I can show you my notes."

"That would be cool."

And again silence reined. Glancing at his watch, Colby resisted the urge to let out a frustrated sigh. It had been almost ten minutes since Charlie had joined them in the backyard.

"Did you know my IQ is only two points lower than yours," Ari remarked a minute later.

"Really?"

"Uh-huh."

As the pair went quiet once again Colby looked up to the sky, remembering why his grandmother told him never to pray for patience. This was getting ridiculous. Still, if it made Ari open up than it was worth it. But as another couple of minutes went by, the agent was about ready to call in one of his back ups to watch them while he got himself a snack. Who knows, he might even be able to prepare and eat an entire meal before these two got around to something important.

"You play chess?" Charlie wondered.

"Who doesn't."

"How about we play a few games while we wait for Don?"

"Okay."

The pair got to their feet and headed inside with Colby right behind them, praying his boss showed up soon. If it took them twenty minutes to contemplate koi, he was not looking forward to watching them play chess. Sometimes he hated guard duty.

* * *

><p>What do you think? Anyone feel sorry for Colby?<p>

One of my friends reminded me of my new years resolution to finish all my active stories, so I will try to get the next part up as soon as possible.


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